Most Developers Can't Implement Array.flat() Correctly | JavaScript Interview Question
In this video, I implement Array.prototype.flat() from scratch in JavaScript, just like the real JavaScript engine.
This is a very popular Frontend Interview Question asked in companies like Google, Amazon, Meta, and startups.
We cover:
• How Array.flat() works internally
• Recursive implementation
• Handling Infinity depth
• Handling sparse arrays (holes)
• Difference between undefined and empty slots
• Polyfill implementation step-by-step
• Interview tips and common mistakes
This video is perfect for:
• Frontend interview preparation
• JavaScript interview prep
• Learning JavaScript internals
• Understanding polyfills
Code implemented matches real JavaScript behavior.
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